On 06/18/2012 04:06 AM, Stephen Warren wrote:

On 06/17/2012 04:11 AM, Roland Stigge wrote:

quoted

of_get_named_gpio_flags() and of_get_named_gpio() return -EPROBE_DEFER if the
respective GPIO is not (yet) available. This is useful if driver's probe()
functions try to get a GPIO whose controller isn't probed yet. Thus, the driver
can be probed again later on.

The function still returns -EINVAL on other errors (parse error or node doesn't
exist). This way, the case of an optional/intentionally missing GPIO is handled
appropriately.

While I agree this is a correct change, it is going to break some
existing code - at least sound/soc/tegra/tegra_{wm8903.c,alc5632.c}.

Can you please tell in which way the patch breaks those drivers?
However, I can see that those drivers solved the same problem in a
different way (deferring of_get_named_gpio(), via the sound init()). So
they could be adjusted to take advantage of new -EPROBE_DEFER.

I'm
happy to send patches for those files though (is this going into 3.5 or
3.6?).

For 3.6 would be best, IMO.

However, have you audited all existing callers (including
indirect, e.g. through plain of_get_named_gpio()) for issues this will
cause?

Thanks for the hint, I searched the code and found

drivers/spi/spi-pl022.c

to be using -ENODEV as indication to return -EPROBE_DEFER from probe().
Will send a patch that adjusts to our of_get_named_gpio_flags() patch
and if it's good, we should join the two.

Some drivers possibly suffer from the same issue that the patch adresses:

drivers/mfd/twl6040-core.c
drivers/staging/nvec/nvec.c
drivers/usb/host/ohci-at91.c
drivers/usb/host/ehci-tegra.c
drivers/usb/gadget/at91_udc.c
drivers/spi/spi-imx.c
drivers/spi/spi-sirf.c
drivers/mmc/host/sdhci-tegra.c
drivers/mmc/host/omap_hsmmc.c
drivers/mmc/host/mxs-mmc.c
drivers/mmc/host/sdhci-esdhc-imx.c
drivers/regulator/tps62360-regulator.c
drivers/regulator/fixed.c

But the breakage therefore exists even before the patch.

Other drivers don't handle the result of of_get_named_gpio*() correctly
at all:

drivers/power/sbs-battery.c

I can help the respective maintainers to work out this issue when we
have the EPROBE_DEFER ready in gpiolib-of.c.

Thanks,

Roland